I am a member of the American Nuclear Society (Virginia section). We have monthly meetings hosting professional speakers in the nuclear biz. Meetings are held at the large Dominion Power executive office building here in Richmond. I actually gave a talk on the fusor back in 2011.

Last week, we had a great speaker, Greg Piefer, founder and head of Shine Medical Technologies. Shine is all about molybdenum 99 and its production for medical use. (Moly 99 half-decays in a few hours to Technicium 99m which is vital for tens of thousands of medical diagnostic tests performed daily around the world. In short, the medicos are hooked on the drug. Currently, there are virtually no suppliers of Moly 99 in the quantities demanded and one of the largest suppliers in Canada is scheduled to shut down next year!!

Moly 99 is a fission product! How is this linked to fusion and who is Dr. Greg Piefer?

At the ANS meeting Greg picked me out of the crowd and introduced himself as the speaker. I told him that I had a fusor doing fusion and that there was fusor.net. Wide-eyed and in an excited tone, he said, "Yes, I know... Richard, you are a legend!"....... I thought, What!??

It turns out Greg was working on his doctorate at the University of Wisconsin, Madison in the 90's and worked with their fusor constantly. Part of that effort had their people read fusor.net to see what we were up to. Greg said he read often and was impressed with what he saw of our efforts. Graduated, Phd in hand, he went to work in the field and quickly realized real money was in a business that had a demand for a forever supply of a product and had a fixed or dwindling group of suppliers.

Moly 99 was it! This boy is sharp. He has figured out a killer process, (killer? Bad choice), for making Moly 99 to supply the world in the quantities needed without a formal, power fission reactor. I will give a short discussion of the epitome of the process.

Make a lot of high speed neutrons......

First, get an 8 foot diameter tank of 19%, U-235 enriched Uranyl sulfate dissolved in water. In the center of this tank, place a natural, un-enriched, U-238 uranium metal pipe. In the center of this pipe you place a 300kev, 15kw, deuteron beam-on-target, tritiated titanium targeted, linear accelerator. Most of the tritium will be knocked out of the target back up the accelerator column where the entire length of the column and target will do D-T fusion. Part of this fusion will take place in velocity space and part on the target.

Multiply the fusion neutrons many times by a bit of fast neutron fission in U-238......... then do a lot of fission, in enriched U-235, but keep it sub-critical....

The neutrons produced in D-T fusion are in the 17mev range and, like the fusor, are all isotropically emitted. These bombard the Uranium pipe surrounding the fusion accelerator, creating fast neutron fission within the Uranium pipe multiplying the neutrons created in fusion. Those fusion neutrons not fissioning in the Uranium pipe plus all the multiplied fission neutrons from the pipe are moderated in the large tank of water dissolved enriched uranyl sulfate solution. This causes a calculated, sub-cruitical U-235 fission system within the tank. (about .94 critical with a flux of about 10e12!)

Draw off your goodie (moly 99)....... Then recirculate........

As this baby cooks, the witches brew is drawn off through a "separation column" which selectively extracts only the moly 99. The brew that is not moly is pumped back into the subcritical reactor tank for more fissioning. This is the basic operation. There are other minor, easy issues already tackled in the process (hydrogen generation in the tank, long term plutonium build up, etc.)

Subcritical means, no explosion hazard, runaway to criticality or control rods needed. Neutrons to keep the process going can be clicked off with an electrical switch. Tank of witches brew self cooling and once turned off, there is no long coast to nuclear or thermal cooling. Shielding is, naturally, required and several of these smallish fusion-fission tank systems are in one building with many shielded enclosures. Thus, if one or more of the systems are down for service etc., others are still cooking and making Moly 99.

This is not pie in the sky or theoretical. It is already tested and works! They are fully funded. They have their licenses all in hand and are building the plant. They have 5 and 10 year contracts with moly 99 distributors to supply them, signed and in hand.

This is Ameican engenuity at work. There was much more detail in the 1 hour talk that Greg gave. Check out the multiple sources of info related to Shine on the Web.

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Congrats. Not many people can brag they're a legend in their own time!

Definitely brilliant of Dr. Piefer to put those steps together.

.94 critical. Just wondering what happens if it hits 1.0? Obviously no Hiroshima, but 19% U-235 in 8 ft. diameter tank of water is still quite a lot of U-235. Big explosion as all the water is turned to steam?

If your experiment needs statistics, you ought to have done a better experiment.

Greg noted that it is physically impossible to cruise to 1.0 criticality from .94 based on the physics and safeguards of his system. He actually proved this to the NRC and that is how he got his licenses.

Others at the meeting brought this up, too. 90% of all in the ANS meeting were Dominion Power employees and were all Nuclear physics, engineers or technicians. Therefore, to them, this was a valid question.

Greg noted that from the the time he applied for all the licensing to the issuance only took 1 year! The audience was stunned.

Why so short a period?.....No power production.....warranted sub critical operation....... and a "special research and development" codicile in NRC regs that allow for easy licensing of such non-power efforts employing under 100 people.

Richard Hull

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Didn't really think it *could* go critical- no doubt it would take more than cranking too hard on the Variac. More of a thought experiment kind of question of what would happen if it did make it to 1.0. Any takers? All I know for sure is I wouldn't want to be the one to clean it up.

If your experiment needs statistics, you ought to have done a better experiment.

Just to be clear- this would never happen at a SHINE facility! However, accidental solution reactors have happened a number of times previously. In such a criticality accident, when the solution hits k=1, there's a large release of heat and radiation, but rarely an explosion. The burst usually drives the solution back under k=1 in a few ms due to the formation of radiolytic gas bubbles and/or steam bubbles. Once these dissipate, the system will go critical yet again (often repeating many, many times). Assuming no new fluid is added, this process will typically extinguish itself by boiling off enough of the solution for the fissile material/moderator ratio and geometric buckling to change enough for the system to go permanently subcritical.

they have it pretty much figured out with hydrogen gas venting which will occur rather constantly and dump tanks of neutron absorbing solutions into the vessel, etc. Believe me, the NRC made them prove no possible k=1 will ever occur. Each of the reactors in the system is small enough that materials can be changed out and the plutonium can be column extracted as the tank is in constant liquid recycle mode to also extract the moly99. Everything that can happen based on years of accumulated fission knowledge is covered.

Richard Hull

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Again, in a cored power reactor, you have frozen, fixed elements. In Shine, you have a tank of uranyl fluid which is constantly pumped out through columns and then pumped back into the tank, (reactor). In short, poisons can be removed or left in as needed to keep K below unity. This is not a fixed, stagnant core reactor. No control rods needed. Poisons are welcome to a point, but can be leached out to keep the reactor humming. These folks are not producing a functioning power reactor and many issues associated with same are just not encountered.

Richard Hull

Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

A fusion reactor as bad as ITER could easily breed enough fuel (uranium) for ten fission nuclear power plants every year even as it produced no net power itself. These ideas have been discussed about fusion and aren't worth the trouble.

As for a fusor to create economic levels of medical isotopes, the flux just isn't there to be viable on a cost bases from all I've seen. But since the Candu reactor already exists, and produces this isotope and many others AND creates power for the grid (a thousand mega watts), I'd think we need more Candu reactors (also near fool proof and woun't melt down with coolant failure) but that is a discussion for another day.

Ready and easy access to plutonium is the biggest danger that any advance system has to face if one wants to get approval and that isn't something the US or any major Government wants available or to deal with. That hurtle is very high bar to this idea.